there is evidence as to the causes of the improvement in general health. Staff-Surgeon T. J. Preston, R.N., stated them thus: " Shorter sea- voyages; greater care not to overcrowd; plentiful and frequent supplies of fresh food; the introduction of condensed water; and the care that is now taken in the general economy and hygiene of the vessels " (Q. 3,253). These seem sufficient to have produced also the comparative improvement in small-pox mortality, especially as the shorter voyages would enable the patients to be soon isolated on shore. The question we now have to consider is, whether the amount of small-pox here shown to exist in both Army and Navy demonstrates the "full security" that re vaccination is alleged to give; whether as a matter of fact our soldiers and sailors, when exposed to the contagion of intense small-pox, do suffer to "any appreciable degree"; and lastly, whether they show any immunity whatever when compared with similar populations who have been either very partially or not at all revaccinated. It is not easy to find a fairly comparable population, but after due consideration it seems to me that Ireland will be the best available, as the statistics are given in the Commissioners' Reports, and it can hardly be contended that it has any special advantages over our soldiers and sailors,—rather the other way. I have therefore given a diagram, XII., in which a dotted line shows the small-pox mortality of the Irish people of the ages 15 to 45 in comparison with the Army and the Navy mortality for the same years. (The figures for this diagram, as regards Ireland, have been calculated from the table at p. 37 of the Final Report, corrected for the ages 15 to 45 by means of Table J. at p. 274 of the Second Report.)
This dotted line shows us that, with the exception of the great epidemic of 1871, when for the bulk of the Irish patients there was neither isolation nor proper treatment, the small-pox mortality of the Irish population of similar ages has been on the average below that of either the Army or the Navy; while if we take
